The effects of thiosulphate and oxygen concentration on tetrathionate oxidation by Thiobacillus X and T. thioparus.

in the 2-week-old rats, ascorbic acid either performs additional functions or performs the same functions as in the other two groups but at accelerated rates. Since the bone marrow is predominantly engaged in the production of blood cells, it is possible that some relationship may exist between the rate of production of blood cells and the quantity of ascorbic acid available to the bone marrow. The concentrations of ascorbic acid in the various organs show a general decrease with age. The liver, which is mainly responsible for its synthesis, also shows a lower concentration of ascorbic acid: this may be due to a decrease in the activities of the enzymes which synthesize it. This may result in lower concentrations in other organs also. The reason for its lower concentration in the liver of older guinea pigs and in the blood cells of older men (Mourhouse & Guerrant, 1952; Kirk & Chieffi, 1953) kept on a normal ascorbic acid diet is not known. Our studies on the rat show that this lower concentration in the organs may be due either to a decrease in its rate of synthesis in the liver or to a decreased rate of its uptake by the organs.